applies his great formula to the problem of determining the mass of a photon.
E = M C2
This familiar equation is actually a special case of the equation Einstein discovered.
It is the special case where the object in question (which we wish to calculate the total energy available) is at rest
Energy = MC2/Sqrt ( 1 - v2/c2)
The last part of the equation tells us that the Energy of an object increases if the object is traveling a velocity of v.
In particular, if the object in question is standing still, (v=0) the equation reduces to the familiar E=mc2 .
Einstein almost never wrote out his famous formula. E=mc2 .
Thus, the page you are looking is one of the great treasures of the scientific world.